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<div class=Section1>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Let’s make sure we are making a
distinction between “differential coefficient of expansion” and “(heat
induced) warping”. All material (Al alloy and low-Fe glass among them)
undergo a change of dimension as a function of temperature. Pure aluminum and
many of its alloys have a differential coefficient of expansion of 2.30e-5 per
degree centigrade difference from 0 degrees centigrade. Low iron tempered glass
has a lower coefficient of 0.84e-5. As a result, both aluminum and glass expand
when heated but glass does so more slowly. Over a 45 degree centigrade temperature
increase (from 25 deg C) there will be a 0.65e-3 change, or less than 1/10<sup>th</sup>
of 1 per cent. Usually this does not create a problem unless the aluminum and glass
are pinned together in some fashion and the length of the bond is long enough to
produce unmanageable changes in dimension. For example a 150 cm length (long
dimension of a PV module) would produce a relative dimension change of 0.1 cm (40
mils). This is manageable I understand given the elastomeric sealant that PV
module manufacturers’ use when applying the frame to the glass/Si/Tedlar sandwich.
</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>What I suspect is the problem is warping,
caused by heating of the aluminum frame. Work hardened metals (including
extruded metal) often have built in stresses due to the forming process. This
stress can be relieved by long term high temperatures, resulting in the metal
piece deforming. I have seen warping as much as 5% in long extruded parts. If
in fact what is happening is warping, then I suspect that warping cannot be
overcome with something like an elastomeric sealant. </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I honestly don’t know if
manufacturers of extruded metal parts put their parts through an annealing
cycle to remove stresses or not.</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<div>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>- Peter</span></font></p>
<p><font size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:
Arial;color:navy'> </span></font></p>
<p class=MsoNormal><img width=67 height=80
src="cid:image003.gif@01C9FA4B.9ED39F50" align=left hspace=12><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>Peter T. Parrish, Ph.D., President<br>
California Solar Engineering, Inc.<br>
820 Cynthia Ave., Los Angeles, CA 90065<br>
CA Lic. 854779, NABCEP Cert. 031806-26<br>
<a href="mailto:peter.parrish@calsolareng.com">peter.parrish@calsolareng.com</a>
<br>
Ph 323-258-8883, Mobile 323-839-6108, Fax
323-258-8885
</span></font><font size=1 color=navy><span style='font-size:9.0pt;color:navy'> </span></font></p>
<p><font size=3 color=navy face="Times New Roman"><span style='font-size:12.0pt;
color:navy'> </span></font></p>
</div>
<div>
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face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
</span></font></div>
<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Joel Davidson<br>
<b><span style='font-weight:bold'>Sent:</span></b> Tuesday, June 30, 2009 9:06
PM<br>
<b><span style='font-weight:bold'>To:</span></b> RE-wrenches<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [RE-wrenches] REC
Solar melt-down</span></font></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<div>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>What frame material has that high a coefficient of
expansion?</span></font></p>
</div>
<blockquote style='border:none;border-left:solid black 1.0pt;padding:0in 0in 0in 3.0pt;
margin-left:2.5pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'>
<div>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>----- Original Message ----- </span></font></p>
</div>
<div style='font-color:black'>
<p class=MsoNormal style='background:#E4E4E4'><b><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial;font-weight:bold'>From:</span></font></b><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <a
href="mailto:nickvida@ymail.com" title="nickvida@ymail.com">Nick Vida</a> </span></font></p>
</div>
<div>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>To:</span></font></b><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'> <a
href="mailto:re-wrenches@lists.re-wrenches.org"
title="re-wrenches@lists.re-wrenches.org">wrenches</a> </span></font></p>
</div>
<div>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>Sent:</span></font></b><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'> Tuesday, June 30,
2009 8:45 PM</span></font></p>
</div>
<div>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>Subject:</span></font></b><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'> [RE-wrenches] REC
Solar melt-down</span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
</div>
<div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>wrenches,<br>
<br>
<br>
the defect in REC panels is the frame expands past the panel and can contract
and break the glass. Unfortunate, but no big deal in a lot of ways. I dont know
if there is another defect, but that one would warrant a recall instead of
replacing a lot of panels. There was also an article about their Oregon plant breaking
a couple hours after it went online. Im glad to see they have done a recal. I
think it is proper and good business. I think thier silicon and wafers are fine
and well made, and we would hopefully find out if they werent because they are
a major supplier of wafers to several manufactures. </span></font></p>
</div>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center>
</span></font></div>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>_______________________________________________<br>
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